Study on the effect of organic sulfur on coal spontaneous combustion based on model compounds

Abstract

The composition and structure of organic sulfur in coal are rather complicated. Thus, no workable method has been adopted to accurately and quantitatively study organic sulfur in coal so far. Coal spontaneous combustion (CSC) is a severe disaster occurring widely in coal industry. It is an extremely complex physical and chemical process as well as a major scientific and technical problem that has always puzzled researchers. Studying the complex chemical reaction of coal by model compounds is a reasonable method extensively recognized and used in the international coal chemistry research field. Model compounds represent certain kinds of specific functional groups in coal. Through an investigation on the reaction mechanism of model compounds, the complex mechanism of coal molecules can be revealed. In this study, in order to better investigate the mechanism of organic sulfur during CSC, representative organic sulfur model compounds containing different organic sulfur functional groups were selected for the low-temperature oxidation experiment and the thermal analysis. Their oxygen consumption amounts and oxidized products concentrations were determined by gas chromatography and infrared analyzer. Besides, the weights and endothermic/exothermic rates of these model compounds during low-temperature oxidation were measured using the thermogravimetry/differential scanning calorimetry (TG/DSC) method. In this way, their oxidative and thermodynamic characteristics were revealed. On this basis, the organic sulfur model compounds were uniformly mixed with the coal samples for the low-temperature oxidation experiment in the hope of exploring its effect on oxygen consumption amounts and indicative gas products during CSC. Finally, the mechanism of the interactions between organic sulfur and other reactive groups in coal during low-temperature oxidization were obtained.